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Chapter 1: Nutrition in Plants

Chapter 2: Nutrition in Animals

Chapter 3: Fibre to Fabric

Chapter 4:Heat

Chapter 5: Acids, Bases and Salts

Chapter 6: Physical and Chemical Changes

Chapter 7: Weather, Climate and Adaptations of Animals to Climate

Chapter 8: Winds, Storms and Cyclones

Chapter 9:Soil

Chapter 10: Respiration in Organisms

Chapter 11:Transportation in Animals and Plants

Chapter 12:Reproduction in Plants

Chapter 13:Motion and Timers

Chapter 14: Electric Current and Its Effects

Chapter 15:Light

Chapter 16:Water: A Precious Resource

Chapter 17: Forests: Our Lifeline

Chapter 18: Wastewater Story

NCERT Solutions for class 7 science chapter 15

Light

NCERT Solutions for Class 7 Science chapter 15 Exercise Question

Question 1
Fill in the blanks:
(a) An /Pathanto/image that cannot be obtained on a screen is called ___________ .
(b) /Pathanto/image formed by a convex is __________ always virtual and smaller in size.
(c) An /Pathanto/image formed by a __________ mirror is always of the same size as that of the object.
(d) An /Pathanto/image which can be obtained on a screen is called a __________ /Pathanto/image.
(e) An /Pathanto/image formed by a concave __________ cannot be obtained on a screen.
Answer
(a) An /Pathanto/image that cannot be obtained on a screen is called virtual /Pathanto/image .
(b) /Pathanto/image formed by a convex is mirror always virtual and smaller in size.
(c) An /Pathanto/image formed by a plane mirror is always of the same size as that of the object.
(d) An /Pathanto/image which can be obtained on a screen is called a real /Pathanto/image.
(e) An /Pathanto/image formed by a concave lens cannot be obtained on a screen.

Question 2
Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) We can obtain an enlarged and erect /Pathanto/image by a convex mirror. (T/F)
(b) A concave lens always form a virtual /Pathanto/image. (T/F)
(c) We can obtain a real, enlarged and inverted /Pathanto/image by a concave mirror. (T/F)
(d) A real /Pathanto/image cannot be obtained on a screen. (T/F)
(e) A concave mirror always form a real /Pathanto/image. (T/F)
Answer

a) False

b) True

c) True

d) False

e) False

Question 3
Match the items given in Column I with one or more items of Column II
Column I Column II
(a) A plane mirror (i) Used as a magnifying glass.
(b) A convex mirror (ii) Can form /Pathanto/image of objects spread over a large area.
(c) A convex lens (iii) Used by dentists to see enlarged /Pathanto/image of teeth.
(d) A concave mirror (iv) The /Pathanto/image is always inverted and magnified.
(e) A concave lens v) The /Pathanto/image is erect and of the same size as the object
vi) The /Pathanto/image is erect and smaller in size than the object.
Answer
Column I Column II
(a) A plane mirror v) The /Pathanto/image is erect and of the same size as the object
(b) A convex mirror (ii) Can form /Pathanto/image of objects spread over a large area.
(c) A convex lens (i) Used as a magnifying glass.
(d) A concave mirror (iii) Used by dentists to see enlarged /Pathanto/image of teeth
(e) A concave lens vi) The /Pathanto/image is erect and smaller in size than the object.

Question 4
State the characteristics of the /Pathanto/image formed by a plane mirror.
Answer
(i) Plane mirror forms an erect and virtual /Pathanto/image.
(ii) height of the /Pathanto/image and object are equal.
(iii)Distance of /Pathanto/image and object from mirror are equal.
(iv) /Pathanto/image formed laterally inverted

Question 5
Find out the letters of English alphabet or any other language known to you in which the /Pathanto/image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.
Answer

A, H, I, M, O, T, U ,V, W These letter appear same when we seen through a plane mirror

Question 6
What is a virtual /Pathanto/image? Give one situation where a virtual /Pathanto/image is formed.
Answer
The /Pathanto/image which formed behind the mirror is called virtual /Pathanto/image.These /Pathanto/image can not obtain on mirror.

Question 7
State two differences between a convex and a concave lens.
Answer
Concave mirror Convax mirror
(a) real /Pathanto/image formed (a) virtual /Pathanto/image formed.
(b)it formed magnified /Pathanto/image (b) it formed diminished

Question 8
Give one use each of a concave and a convex mirror.
Answer
Concave mirror is used in solar furnaces to conserve sunlight.
Convex mirror is used as side view mirror in vehicles

Question 9
Which type of mirror can form a real /Pathanto/image?
Answer
Concave mirror

Question 10
Which type of lens forms always a virtual /Pathanto/image?
Answer
Concave lens

Choose the correct option in Questions 11-13:

Question 11
A virtual /Pathanto/image larger than the object can be produced by a
(i) concave lens (ii) concave mirror (iii) convex mirror (iv) plane mirror

Answer
(ii) concave mirror

Question 12
David is observing his /Pathanto/image in a plane mirror. Die distance between the mirror and his /Pathanto/image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his /Pathanto/image will be
(i) 3 m (ii) 5 m (iii) 6 m (iv) 8 m

Answer

(iii) 6 m

Question 13
The rear view mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rear mew mirror the /Pathanto/image of a truck parked behind his car. The speed at which the /Pathanto/image of the truck appears to approach the driver will be
(i) 1 m/s (ii) 2 m/s (iii) 4 m/s (iv) 8 m/s

Answer

(ii) 4 m/s